twong-flutter/lib/pages/product/product_list.dart

import 'package:flutter/material.dart';
import 'package:twong/api/index.dart';
import 'package:twong/utils/index.dart';
import 'package:twong/router/index.dart';
import 'package:twong/models/index.dart';
import 'package:twong/widgets/sliver_bar.dart';
import 'package:twong/widgets/search_bar.dart';
import 'package:twong/widgets/product_item.dart';

class ProductListPage extends StatefulWidget {
  final String _keyword;

  ProductListPage(this._keyword, {Key key}): super(key: key);

  @override
  State<StatefulWidget> createState() {
    return _ProductListPageState(_keyword);
  }
}

class _ProductListPageState extends State<ProductListPage> {
  final String _keyword;
  ScrollController _scrollController = ScrollController();

  _ProductListPageState(this._keyword);

  Future<List<Product>> _getSearchData() {
    return Network.inst.search(_keyword);
  }

  Widget _buildList () {
    return FutureBuilder(
      future: _getSearchData(),
      builder: (BuildContext context, AsyncSnapshot snapshot) {
        if (snapshot.connectionState == ConnectionState.done) {
          List<Product> data = List<Product>();
          data = snapshot.data;
          if (data.length > 0) {
            return SliverPadding(
              padding: EdgeInsets.all(2),
              sliver: SliverGrid(
                gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
                  crossAxisCount: 2,
                  childAspectRatio: 5 / 6,
                ),
                delegate: SliverChildBuilderDelegate((context, index) =>
                    ProductItem(index, data), childCount: data.length),
              ),
            );
          } else {
            return SliverToBoxAdapter(
                child: Container(
                  padding: EdgeInsets.only(top: 200),
                  child: Text('抱歉，没有找到您想要的宝贝！', textAlign: TextAlign.center,),
                )
            );
          }
        }else {
          return SliverToBoxAdapter(
            child: Container(
              padding: EdgeInsets.only(top: 200),
              child: Center(
                child: CircularProgressIndicator(),
              ),
            ),
          );
        }
      },
    );
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: SearchBar(GestureDetector(
          onTap: () { Navigator.pushNamed(context, RouteNames.home); },
          child: Container(
            child: Center(child: Icon(Icons.arrow_back_ios_outlined, color: Colors.white, size: 20.px)),
          ),
        )),
      body: CustomScrollView(
        controller: _scrollController,
        slivers: <Widget>[
          SliverBar(),
          _buildList(),
        ],
      ),
      floatingActionButton: Container(
        width: 40,
        height: 35,
        decoration: BoxDecoration(
          borderRadius: BorderRadius.circular(3),
          color: Color.fromRGBO(12, 12, 12, 0.6),
        ),
        child: IconButton(
          icon: Icon(Icons.arrow_upward, color: Colors.white),
          onPressed: () {
            _scrollController.animateTo(0, duration: Duration(seconds: 1), curve: Curves.easeInOut);
          },
        ),
      ),
    );
  }
}